6.1-stable review patch. If anyone has any objections, please let me know.
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From: Naohiro Aota naohiro.aota@wdc.com
commit e30729d4bd4001881be4d1ad4332a5d4985398f8 upstream.
__btrfs_add_free_space_zoned() references and modifies bg's alloc_offset, ro, and zone_unusable, but without taking the lock. It is mostly safe because they monotonically increase (at least for now) and this function is mostly called by a transaction commit, which is serialized by itself.
Still, taking the lock is a safer and correct option and I'm going to add a change to reset zone_unusable while a block group is still alive. So, add locking around the operations.
Fixes: 169e0da91a21 ("btrfs: zoned: track unusable bytes for zones") CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/free-space-cache.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
--- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2677,15 +2677,16 @@ static int __btrfs_add_free_space_zoned( u64 offset = bytenr - block_group->start; u64 to_free, to_unusable; int bg_reclaim_threshold = 0; - bool initial = ((size == block_group->length) && (block_group->alloc_offset == 0)); + bool initial; u64 reclaimable_unusable;
- WARN_ON(!initial && offset + size > block_group->zone_capacity); + spin_lock(&block_group->lock);
+ initial = ((size == block_group->length) && (block_group->alloc_offset == 0)); + WARN_ON(!initial && offset + size > block_group->zone_capacity); if (!initial) bg_reclaim_threshold = READ_ONCE(sinfo->bg_reclaim_threshold);
- spin_lock(&ctl->tree_lock); if (!used) to_free = size; else if (initial) @@ -2698,7 +2699,9 @@ static int __btrfs_add_free_space_zoned( to_free = offset + size - block_group->alloc_offset; to_unusable = size - to_free;
+ spin_lock(&ctl->tree_lock); ctl->free_space += to_free; + spin_unlock(&ctl->tree_lock); /* * If the block group is read-only, we should account freed space into * bytes_readonly. @@ -2707,11 +2710,8 @@ static int __btrfs_add_free_space_zoned( block_group->zone_unusable += to_unusable; WARN_ON(block_group->zone_unusable > block_group->length); } - spin_unlock(&ctl->tree_lock); if (!used) { - spin_lock(&block_group->lock); block_group->alloc_offset -= size; - spin_unlock(&block_group->lock); }
reclaimable_unusable = block_group->zone_unusable - @@ -2726,6 +2726,8 @@ static int __btrfs_add_free_space_zoned( btrfs_mark_bg_to_reclaim(block_group); }
+ spin_unlock(&block_group->lock); + return 0; }